Physics · Motion In A Plane · NEET
No. After launch, gravity acts only downward, so there is zero force in the horizontal direction (air resistance is ignored). This means the horizontal velocity component v_x = v_o cos(theta) stays exactly the same from launch to landing. Only the vertical component changes.
At the top, the vertical velocity v_y = 0 (the ball momentarily stops rising). But the horizontal velocity is still there. So the speed at the highest point is NOT zero, it equals the horizontal component v_x = v_o cos(theta). This is the single most tested idea in NEET on this topic.
Because the two directions are independent. NCERT states that a 2D motion with constant acceleration can be treated as two separate 1D motions. Horizontal: uniform velocity (a_x = 0). Vertical: uniform acceleration (a_y = -g). Solving each with simple 1D equations is far easier than handling the curved path directly.
No. Even at the highest point, where v_y = 0, the acceleration is still g = 9.8 m/s downward. Velocity being zero (vertically) does not mean acceleration is zero. Gravity never switches off during flight.
Constant: horizontal velocity v_x, and the acceleration (always g downward). Changing: vertical velocity v_y (decreases going up, increases coming down), the overall speed, and the direction of motion. At launch and at the same height on the way down, the speed is equal.
A ball is projected with a velocity 10 m/s at an angle of 60 degrees with the vertical direction. Its speed at the highest point of its trajectory will be:
A ball is projected from point A with a velocity 20 m/s at an angle 60 degrees to the horizontal direction. At the highest point B of the path, the speed v (in m/s) of the ball will be:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
A projectile is any object that is in flight after being thrown or launched, and then moves only under gravity, for example a cricket ball, a football, or a bullet. It has no engine pushing it and we ignore air resistance.
If launched with speed v_o at angle theta to the horizontal, the horizontal component is v_x = v_o cos(theta) and the vertical component is v_y = v_o sin(theta). The horizontal component stays constant; the vertical component changes as v_y = v_o sin(theta) - g t.
Yes. The horizontal direction has zero acceleration, but the vertical direction always has acceleration g = 9.8 m/s downward. So overall the motion is accelerated throughout the flight.
A parabola. This comes from combining constant horizontal velocity with uniformly accelerated vertical motion, giving an equation of the form y = a x + b x squared, which is a parabola. See the equation of trajectory for the full derivation.
NEET repeatedly asks about the speed at the highest point, and about time of flight, height, and range, which all come directly from splitting velocity into horizontal and vertical components. Getting the component idea right unlocks the whole chapter.
